Apparatus and Method for Generating Electric Power from a Subsurface Water Current

ABSTRACT

A subsurface power generating system in one embodiment includes a frame, an electric generator supported by the frame and operably connected to a first vertical rotor, another electric generator supported by the frame and operably connected to a second vertical rotor, a first louver operably connected to the first vertical rotor and including a front side, and a back side, and pivotable between a first position whereat the backside is in contact with a first pivot limiting structure, and a second position whereat the backside is not in contact with the first pivot limiting structure, and a second louver operably connected to the second vertical rotor and including a front side, and a back side, and pivotable between a third position whereat the backside is in contact with a second pivot limiting structure, and a fourth position whereat the backside is not in contact with the second pivot limiting structure.

This application is a divisional application of U.S. patent applicationSer. No. 11/519,607, filed Sep. 12, 2006, which claims the benefit ofprovisional U.S. Patent Application No. 60/716,063, filed on Sep. 12,2005.

FIELD

The present invention relates generally to the field of hydroelectricpower generation, and, more particularly, to an apparatus and method forgenerating electric power from a subsurface water current.

BACKGROUND

The wealth of the United States has been created largely through theexploitation of cheap energy provided by the past abundance of fossilfuels. Because of the increasing shortages of natural gas in NorthAmerica, the continued reliance on oil suppliers located volatileregions, the approaching worldwide shortages of oil, and because of thegrowing danger of global warming that may be caused by the combustion offossil fuels, clean reliable sources of renewable energy are needed.

Many of the efforts to develop power generation systems fueled byrenewable energy sources have been focused on wind energy. Although windpowered generating systems provide many benefits, they have asignificant drawback. Specifically, wind direction and speed are in aconstant state of flux. Wind speeds can fluctuate hourly and have markedseasonal and diurnal patterns. They also frequently produce the mostpower when the demand for that power is at its lowest. This is known inthe electricity trade as a low capacity factor. Low capacity factors,and still lower dependable on-peak capacity factors, are notableshortcomings of wind power generation.

In contrast to the winds, some deep ocean currents are driven largely byrelatively steady Coriolis forces. The fact that such ocean currents arenot subject to significant changes in direction or velocity makessub-sea power generation somewhat more desirable than the intermittentpower produced by wind-driven turbines. The book, Ocean Passages of theWorld (published by the Hydrographic Department of the BritishAdmiralty, 1950), lists 14 currents that exceed 3 knots (3.45 mph), afew of which are in the open ocean. The Gulf Stream and the Kuro Shioare the only two currents the book lists having velocities above 3 knotsthat flow throughout the year. Both of these currents are driven by theCoriolis force that is caused by the Earth's eastward rotation actingupon ocean currents produced by surface trade winds. Because thesecurrents are caused largely by the Earth's rotation, they should remainconstant for a substantial period barring significant changes in localgeography.

The Gulf Stream starts roughly in the area where the Gulf of Mexiconarrows to form a channel between Cuba and the Florida Keys. From therethe current flows to the northeast through the Straits of Florida,between the mainland of the United States and the Bahamas, flowing at asubstantial speed for some 400 miles. The peak velocity of the GulfStream is achieved off of the coast of Miami, Fla., where the GulfStream is about 45 miles wide and 1,500 feet deep. There, the currentreaches speeds of as much as 6.9 miles per hour at a location betweenKey Largo, Fla. and North Palm Beach, Fla., and less than 18 miles fromshore. Farther along it is joined by the Antilles Current, coming upfrom the southeast, and the merging flow, broader and moving moreslowly, continues northward and then northeastwardly, as it roughlyparallels the 100-fathom curve as far as Cape Hatteras, N.C.

The Kuro Shio is the Pacific Ocean's equivalent to the Gulf Stream. Alarge part of the water of the North Equatorial current turnsnortheastward east of Luzon and passes the east coast of Taiwan to formthis current. South of Japan, the Kuro Shio flows in a northeasterlydirection, parallel to the Japanese islands, of Kyushu, Shikoku, andHonshu. According to Ocean Passages of the World, the top speed of theKuro Shio is about the same as that of the Gulf Stream. The GulfStream's top flow rate is 156.5 statute miles per day (6.52 mph) and theKuro Shio's is 153 statute miles per day (6.375 mph).

Other possible sites for the underwater generators are the EastAustralian Coast current, which flows at a top rate of 110.47 statutemiles per day (4.6 mph), and the Agulhas current off the southern tip ofSouth Africa, which flows at a top rate of 139.2 statute miles per day(5.8 mph). Another possible site for these generators is the Strait ofMessina, the narrow opening that separates the island of Sicily fromItaly, where the current's steady counter-clockwise rotation is producedprimarily by changing water densities resulting from evaporation in theMediterranean. Oceanographic current data may suggest other potentialsites.

Submersible turbine generating systems can be designed to efficientlyproduce power from currents flowing as slowly as 3 mph—if that flow rateis consistent—by increasing the size of the turbines in relation to thesize of the generators, and by adding more gearing to increase the shaftspeeds to the generators. Because the Coriolis currents can be verysteady, capacity factors of between 70 percent and 95 percent may beachievable. This compares to historical capacity factors forwell-located wind machines of between 23 percent and 30 percent. Becausea well-placed submersible water turbine will operate in a current havingeven flow rates, it may possible for it to produce usable currentpractically one hundred percent of the time.

Moreover, increasing human ingress into the oceans makes undersea powergeneration desirable. Historically, submarines have had to periodicallysurface and dock at shore based ports for maintenance that has includedrecharging or replacing electric batteries and/or receiving temporaryelectric power during the maintenance of their on-board generators. Suchneeds to periodically travel to shore based facilities have undesirablylimited the mission capabilities of many submarines. A suitable deep seapower generation facility could provide opportunities for submarines toobtain electric power for maintenance while remaining submerged andwithout diversion from the open ocean to a shore location. Additionally,as the number of underwater scientific observatories increases, so doesthe need to generate power for the observatories at the observatorysites. Further, whether engaged in military, scientific, commercial, orrecreational activities humans need potable water. Potable water can beproduced from sea water, but such production facilities typicallyrequire electricity.

Although the needs are numerous, viable sub-sea power generation haspresented notable challenges. For example, rotating electric generatorsproduce heat. The electric current flowing through the conductors, bothin the stator and rotor, produces heat because of the electricalresistance. In addition, heat is generated in the steel of the rotorarmature core by the changing magnetic fluxes and bearing, shaft, andgear friction produces heat as well. Although the heat loss in largegenerators is typically only on the order of about 1 percent of output,this is still considerable. For example, a pair of generators producing1,200 kW might have a loss of 12 kW, which is equivalent to 40,973 BTUper hour. Therefore, a liquid cooling system is desirable fordissipation of heat produced by a sub-sea power generation system.Additionally, maintaining proper horizontal, vertical, and azimuthalturbine positioning relative to ocean current depths and directions foroptimizing capacity factors in operation of sub-sea power generationsystems has been challenging. Another challenge has been that deeplysubmerging power generation units has made them less readily accessiblefor servicing and repair.

SUMMARY

A subsurface power generating system in one embodiment includes a frame,a first electric generator supported by the frame and operably connectedto a first vertical rotor, a second electric generator supported by theframe and operably connected to a second vertical rotor, a first louveroperably connected to the first vertical rotor and including a frontside, and a back side, and pivotable between a first position whereatthe backside is in contact with a first pivot limiting structure, and asecond position whereat the backside is not in contact with the firstpivot limiting structure, and a second louver operably connected to thesecond vertical rotor and including a front side, and a back side, andpivotable between a third position whereat the backside is in contactwith a second pivot limiting structure, and a fourth position whereatthe backside is not in contact with the second pivot limiting structure.

In another embodiment, a method of generating electrical power from awater current includes positioning a first louver within a watercurrent, impinging a front side of the first louver with the watercurrent, pivoting the first louver into contact with a first pivotlimiting structure using a first force generated by the impinging watercurrent, transferring a second force from the water current to the firstpivot limiting structure, and rotating a first vertical rotor operablyconnected to a first electrical generator with the transferred secondforce.

In a further embodiment, a subsurface power generating system includes aframe, a first electric generator supported by the frame, the firstelectric generator operably connected to a first vertical rotor, a firstlouver operably connected to the first vertical rotor and including afront portion, and a back portion, and pivotable between a firstposition whereat the back portion is in contact with a first pivotlimiting structure, and a second position whereat the back portion isnot in contact with the first pivot limiting structure, and a first barextending through the first louver and defining an axis of rotation forthe first louver such that the first louver is cantilevered toward thesecond position from the first position in response to a currentcontacting the back portion of the first louver and cantilevered towardthe first position from the second position in response to the currentcontacting the front portion of the louver.

The above-noted features and advantages of the present invention, aswell as additional features and advantages, will be readily apparent tothose skilled in the art upon reference to the following detaileddescription and the accompanying drawings, which include a disclosure ofthe best mode of making and using the invention presently contemplated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of an exemplary manned subsurfaceelectric power generation station in accordance with principles of thepresent invention;

FIG. 2 shows a partial cutaway view of a generating node of the stationof FIG. 1 showing a number of modular generators coupled to a pluralityof universal gears through individually controllable clutch mechanisms;

FIG. 3 shows schematic view of an anchoring and positioning system usedwith an alternative manned subsurface electric power generation stationin accordance with principles of the present invention;

FIG. 4 shows a schematic view of a control network for the varioussubsystems of the manned station of FIG. 1 in accordance with principlesof the present invention;

FIG. 5 shows a top plan view of the station of FIG. 1;

FIG. 6 is a partial cutaway view of the station of FIG. 1 showingadditional detail of the power generating node of FIG. 2;

FIG. 7 shows a schematic of the placement of crossbars with the louversused in the louver panels of the station of FIG. 1 which reduce the needfor maintenance on the louvers; and

FIG. 8 shows a partial cutaway view of the dry transfer node andelevator system of the station of FIG. 1.

DETAILED DESCRIPTION

Like reference numerals refer to like parts throughout the followingdescription, the accompanying drawings, and the claims.

FIG. 1 shows a perspective view of an exemplary sub-sea electric powergeneration station 100 according to the present invention. The station100 is designed to operate 24 hours per day and 365 days per year whiletotally submerged to supply power to an onshore power grid through anumbilical (not shown). The station 100 is marine creature, biomass, andnavigational friendly, and is suitable for, among other locations,geographic locations where fairly constant, vector specific sub seacurrents are present. It should be appreciated that there are numerousworldwide locations (e.g., North American Gulf Stream areas such as theFlorida, Georgia, and South Carolina coasts, among others) whereconstant, vector specific, sub-sea currents can be harnessed to generateelectricity. In addition to the ability to generate electrical energy,the station 100 is capable of producing significant quantities ofpotable water.

The station 100 includes a neutrally buoyant, manned, one atmosphere,frame 102. The frame 102 includes a generally horizontally orientedupper triangularly shaped pressure resistant structure 104, a generallyhorizontally oriented lower triangularly shaped pressure resistantstructure 106, and three substantially hollow generally verticallyoriented legs or “spars” (a first spar 108, a second spar 110, and athird spar 112) extending between the structure 104 and the structure106.

The triangularly shaped structures 104 and 106 and the spars 108, 110and 112 are generally cylindrical in construction and manufactured toappropriate standards such as American Society of Mechanical Engineers(ASME) standards for a pressure vessel for human occupancy (PVHO-2,section VIII, Division I), National Board, American Bureau of Shipping(ABS) and U.S. Coast Guard (USCG) standards. The frame 102 is configuredto be neutrally buoyant. Neutral buoyancy may be achieved by a varietyof combinations of water displacement by the station 100 and permanentand variable buoyancy including the use of “hard” and “soft” ballasttanks and syntactic foam.

The upper triangular structure 104 in this embodiment provides livingquarters similar to those found onboard a merchant vessel includingberthing quarters, restrooms, showers, common rooms, off duty rooms,food preparation and storage areas, a small infirmary, a communicationand media room, an exercise area, etc. Additionally, the uppertriangular structure 104 provides a storage area for emergency equipmentsuch as an emergency escape pod and a one atmosphere absolutetransfer-under-pressure (One ATATUP) module.

The lower triangular structure 106 provides additional space for storageand equipment. By way of example, water generators (either reverseosmosis (“R/O”) or distilling type), a sanitary station, water heaters,control equipment, fire suppression systems (“FSS”), a decompressionchamber, a diver lock out compartment (“DLOC”), remote vehicle lock outports (“ROVLOCs”), air chargers and environmental control units (“ECU”)are provided with the station 100. The environmental control unitsinclude oxygen generators, scrubbers and burners. The lower triangularstructure 106 further houses tanks for the storage of potable water,pressurized air and oxygen and one or more heat exchanger systems forthermal cooling of rotating machine parts and for using the heatgenerated by the machine parts to heat the station. Additionally, abattery provides a back-up power supply in case power generation isdisrupted and the power grid is not available.

The station 100 includes six nodes. Nodes 114 and 116 are joined by thespar 110, nodes 118 and 120 are joined by the spar 112 and nodes 122 and124 are joined by the spar 108. Six additional spars further join thevarious nodes. Specifically, along the upper structure 104 spar 126joins nodes 122 and 114, spar 128 joins nodes 114 and 118, and spar 130joins nodes 118 and 122. Along the lower structure 106 spar 132 joinsnodes 124 and 116, spar 134 joins nodes 116 and 120, and spar 136 joinsnodes 120 and 124. Each of the passageways between the nodes and thespars may be sealed by a watertight door (not shown) to isolate thevarious areas in case of flooding or other emergency. The nodes 116, 120and 124 are secured to pylons 117, 121 and 125, respectively. The pylons117, 121 and 125 are anchored in the seafloor.

The spar 110 and the spar 112 serve as housings for vertical driveshafts. With reference to FIGS. 1 and 2, a drive shaft 138 extendsbetween the nodes 116 and 114. The drive shaft 138 is coupled to threelouver panels 140, 142 and 144. The louver panels 140, 142 and 144 arerotatably supported by the spar 110. The drive shaft 138 drives a numberof modular electrical generators such as modular generators 146. Thespar 112 is similarly configured with louver panels 141, 143 and 145.Thus, in this embodiment each power generator node 114, 116, 118, and120 houses sixteen stacked modular generator units.

The spar 108 is outfitted with instrumentation and blade/vanemicroprocessors that control closing of the various louver panels suchas louver panels 140, 141, 142, 143, 144 and 145 in the proper sequenceto maximize the extraction of kinetic energy from the water current andcontrols opening of the various louver panels in order to minimize thesurface resistance of the louvers that are rotating back into the“driven position.” The lower portion of this instrumentation spar 108also provides a one-atmosphere scientific observation station.

FIG. 3 shows an alternative station 300 with various components removedto more clearly show an anchoring and positioning system 150. Theanchoring and positioning system 150 includes a massive circular “mudpad” type anchor 152 that is buried in the seafloor 154 usinghigh-pressure water jets as is known to those of ordinary skill in therelevant art.

The system 150 further includes three stainless steel “tension leg”cables 156, 158 and 160 which extend from the mud pad 152 and are heldin tension by respective redundant, syntactic foam filled, stainlesssteel subsurface buoys 162, 164 and 166. The length of the cables 156,158 and 160 is selected such that the subsurface buoys 162, 164 and 166are not maintained at a depth to pose a significant impediments tosurface going vessels (under power or tow) in any sea state.Alternatively, the station 300 may be located in an area where fishingand navigation are restricted to avoid entanglement or damage. Eachindividual stainless steel tension leg cable 162, 164 and 166 passesthrough the corresponding vertical spar 310, 308 or 312 of the station300. The cables 162, 164 and 166 of the system 150 are equipped withemergency buoyancy devices so any portions of damaged/fouled cable willfloat to the surface rather than sink and potentially entangle in thelouver panels.

The anchoring and positioning system 150 further includes large spoolwinches and/or other suitable hydraulic traction devices (not shown)located inside each of the respective spars 308, 310 and 312. Theanchoring and positioning system 150 submerges the station 300 to theselected operational depth by employing the winches to draw in cable andpull the station 300 toward the sea floor 154. Conversely, the winchesmay also be used to allow the station 300 to “crawl” from the selectedoperational depth up to the tension leg buoys 162, 164 and 166. Thevariable ballast tanks may be used to provide the station 300 withnegative or positive buoyancy to reduce the load on the winches duringthese operations.

Additionally, the anchoring and positioning system 150 can rapidlysemi-surface the station 300 to a shallow depth by releasing the cables156, 158 and 160 and using the variable ballast tanks to provide apositive buoyancy. In either event, the station 300 may be positioned tojust below the surface 168 of the ocean where it can be serviced byconventional diving equipment.

The station 300 also includes a tethered one-atmosphere “elevator” pod170 that can be surfaced and submerged from the station 300 by releasingor retracting a cable from a cable winch mounted on the station 300. Thepod 170 can be used for transporting equipment from the surface 168 tothe submerged station 300. The pod cable is equipped with emergencybuoyancy devices so any portions of damaged/fouled cable will float tothe surface rather than sink and potentially entangle in the panelslouver panels.

Returning to FIG. 1, the station 100 is further configured to producelarge quantities of potable water. In addition to employing the louverpanels to generate electric power, the system employs either generatedelectrical power or the mechanical force of the rotating louver panels140, 141, 142, 143, 144 and 145 to power high pressure water pumps thatpull in ambient sea water 660 through marine biology friendly (suctionbreak) filters and to force the high pressure sea water through areverse osmosis membrane to produce fresh potable water. Alternatively,the sea water may be distilled. If needed, the potable water may bemicro gas chlorinated. The potable water is then available forconsumption on station 100 during manned operations and/or may be pumpedto a mainland water facility via buried pipelines.

The station 100 further includes a brine diffusion system, a holdingtank that collects the brine (“flush”) of the reverse osmosis process,and a pump that injects the brine into the brine diffusion system. Thebrine diffusion system includes long runs of perforated pipe and a pumpthat forces a strong flow of ambient seawater through the pipe. Thesystem 400 injects the brine solution into the pipes in metered dosesand the brine then diffuses into the surrounding sea water through theperforated piping in a controlled manner so as to not salt poison marinelife. This ameliorates undesirable production of salt clouds in thewater column that could be poisonous to marine life. Preferably, thebrine diffusion piping is located downstream from the station 100.

Operations of the station 100 are controlled through a station computernetwork 170 shown in FIG. 4. The network 170 includes a user interface172, a microprocessor 174 and a memory 176. The microprocessor 174 isprogrammed to monitor and control various functions related to theoperation of the station 100. By way of example, various sensors 178associated with the production of power may be monitored. The sensors178 in this embodiment include sensors that produce outputscorresponding to the rotational position of the louver panels 140, 141,142, 143, 144 and 145.

The microprocessor 174 also monitors environmental conditions throughsensors 180 including atmospheric conditions within the station 100. Thesensors 182 provide signals corresponding to conditions upstream of thestation 100. The sensors 182 in this embodiment are AQUADOPP® currentmeters commercially available from NortekUSA of Annapolis, Md. Thesensors 182 provide outputs indicative of water temperature and watervelocity. The sensors 182 are located in the current path upstream ofthe station 100.

The microprocessor 74 is further programmed to provide various controlfunctions. By way of example, the microprocessor 174 provides controlsignals to various systems 184 used to maintain the environment of thestation 100 habitable. The systems 184 include the heating, ventilationand air conditioning systems. The microprocessor further controls themachinery associated with fire suppression systems 186, communicationsystems 188, and auxiliary systems 190.

The microprocessor further controls various systems 192 associated withpower generation including control of the louver panels. Control of thelouver panels is described with reference to FIG. 5. The water currentis moving in the direction indicated by the arrow 194. The speed of thecurrent is sensed by the sensors 182 and a signal is passed to themicroprocessor 174. A signal indicative of the position of the louverpanels 140, 141, 142, 143, 144, and 145 is passed to the microprocessor174 from the sensors 178. The microprocessor 174 is programmed tocompute a projected impact time based upon the received input for eachof the louver panels 140, 141, 142, 143, 144, and 145.

In other words, as the louver panels 140, 141, 142, 143, 144, and 145rotate about the spars 110 and 112 in the direction indicated by arrows195 and 197, the microprocessor 174 projects the time at which a linedrawn from the respective spar 110 or 112 through the louver panels 140,141, 142, 143, 144, and 145 is pointed directly toward the directionfrom which the current is coming (referred to herein as aligned with thecurrent). In FIG. 5, the louver panel 140 is nearly aligned with thecurrent. Thus, as the louver panels 140, 141, 142, 143, 144, and 145continue to rotate past the point at which they are aligned with thecurrent, the microprocessor 174 issues a control signal which causes thelouvers 146 on the particular louver panel to move to a closed position,creating a relatively large surface for receiving kinetic energy fromthe current.

The current continues to provide force against the closed louver panelsuntil the louver panel is aligned with the current on the downstreamside. In FIG. 5, the louver panel 141 is nearly aligned with the currenton the downstream side. Beyond this position, any force of the currenton the louver panel acts to slow the rotation of the louver panels.Accordingly, the microprocessor 174 issues a control signal causing thelouvers 196 (see FIG. 2) on panels that are aligned with the current onthe downstream side to open thereby reducing the effective surface areaof the louver panel.

Those of ordinary skill in the art will further appreciate that thetorque on the station 100 from the louver panels 141, 143 and 145 arecountered by the torque on the station 100 from the louver panels 142,144 and 146.

In one embodiment, the microprocessor 174 is configured to determinepredictive “attack angle” and “rate of attack.” This calculationincorporates the rotational speed of the louver panels along with thetransition speed of the louvers between the open and closed position tooptimize the rotational speed of the louver panels.

The microprocessor 174 may further be used to control the louvers 196 toa “full feather” position wherein the controlled louvers 196 move to afull open position to aid in slowing/stopping rotation of the louverpanels. Another controlled position is a “full tilt” position where allof the louvers 196 on each of the louver panels are controlled to afully closed position to provide relatively low vertical resistance whenchanging the depth of the station 100 such as for semi-surfacing thestation 100 for repairs. The louvers 196 may further be controlled to a“selective feather” position where one of the louvers 196 is set to afull open position and locked to allow repair of the motion controlsystem for that louver while the rest of the louvers continue tofunction as normal in power generation.

The microprocessor 174 also provides control functions for the powergeneration equipment in the power generating nodes 114, 116, 118 and120. Referring to FIG. 6, the power generating node 114 includes fourlevels of modular generators 146. Each level includes four modulargenerators 146 arranged about the power axle 138. The power axle 138 iscoupled to four universal gears 198, 200, 202 and 204. Each of thegenerators 146 is coupled to the universal gear 198, 200, 202 or 204that is on the same level as the modular generator 146 by a clutch 206.The microprocessor 174 issues control signals for engaging ordisengaging the individual clutches 206. Accordingly, each of themodular generators 146 may be individually removed from operation toperform maintenance or for replacement without affecting the operationof the remaining thirty-one modular generators 146 in the generatingnode 114.

Maintenance concerns also factor into the construction of the louvers196. By way of example, FIG. 7 shows a schematic view of a louver 206and a louver 208. The position of the louvers 206 and 208 are controlledthrough crossbars 210 and 212, The crossbars 210 and 212 are positionedsuch that the louvers 206 and 208 are somewhat cantilevered toward anopen position when current flowing in the direction of the arrow 214impacts the front surfaces 216 and 218, respectively. Conversely, whencurrent flowing in the direction of the arrow 220 impacts the backsurfaces 222 and 224, the louvers 206 and 208, respectively, experiencea force moving them toward a closed position. This configurationincreases the operational efficiency of the louver panels and reducesthe forces on the systems used to control the louvers. The louvers 206and 208 in this embodiment are also configured to be neutrally buoyantwhen the station 100 is at the desired depth. Thus, less force is placedupon the various components further reducing maintenance requirements.

The auxiliary systems 190 controlled by the microprocessor 174 includean elevator system provided in the spar 108. As shown in FIG. 8, thespar 108 encloses an elevator shaft 220 which extends between the node122 and the node 124. The elevator allows for movement of personnel,supplies and equipment between the upper structure 104 and the lowerstructure 106. The spars 126, 128, 130, 132, 134 and 136 may further besupplied with tracks or guide rails for use in moving equipment orsupplies throughout the station.

The elevator shaft is located beneath a dry water skirt 222. Thetransfer skirt 222 is configured to be used with a vehicle equipped witha high pressure water sweep and a rotary scrub brush. The high pressurewater sweep and rotary scrub brush are used to clear biofouling andother debris from the dry transfer skirt 222. The vehicle then settlesonto the dry transfer skirt 222 with the aid of stab pins to provide forproper alignment. A seal on the underside of the vehicle provides awatertight seal between the vehicle and the dry transfer skirt 222. Oncethe vehicle is properly positioned, the space within the seal andbetween the vehicle and the dry transfer skirt 222 is dewatered. Thedewatering process lowers the pressure between the vehicle and the drytransfer skirt 222. Accordingly, a tight seal is maintained by the forceof the ambient sea pressure acting upon the vehicle.

In accordance with one embodiment, the station 100 is situated at awater depth of 650 to 2,500 feet of seawater (“FSW”). This depth placesthe station 100 well below the mean water surface in a 100-year stormrisk scenario. When incorporating the anchoring and positioning system150 in 650 FSW, the mud pad 152 is buried at a depth of around 45 feetbelow the seafloor 154 and the three subsurface buoys 162, 164 and 166that terminate the respective stainless steel tension leg cables 156,158 and 160 are at a minimum of depth of around 165 FSW, still below themean water surface in a 100-year storm risk scenario.

A manned submersible may be used to effect crew changes, delivery offood, hard mail, replacement parts, and to remove sick or injuredstation workers, and to deliver and replace scientists visiting thescientific observation station. Thusly located well below the “actionlayer” of the ocean, the station 100 is not significantly impacted byadverse surface/semi-surface conditions such as tsunamis, hurricanes,solar flares, war, etc. The station 100 is thusly also a difficulttarget for potential terrorism. Further, it should be noted that thelouver panels 140, 141, 142, 143, 144 and 145 may open, close, androtate slowly enough to ameliorate adverse impacts on marine life. Thestation 100 also includes an underwater sound broadcasting systemconfigured to produce sounds at levels and frequencies to induceaversion/diversion maneuvers in most forms of marine life. The impact ofinvertebrates jellyfish, etc.) on the support columns, and bladesurfaces would be comparable to the impact seen on offshore oilproduction structures or sunken ships.

Additionally, in operation the station 100 may provide an auxiliarypower dock for submarines to fill their power and fresh water needsduring a “submerged power down of their onboard power plants forrepair/maintenance, and the station 100 may provide a high voltage powersource for long range hydrophonic sub-sea listening/tracking/signalrepeating systems.

Additionally, as the station 100 is substantially a large metalstructure submerged in reasonably cool water (i.e., on the order of 39degrees F. at a depth of around 650 FSW), the temperature of the ambientwater 660 facilitates cooling of the rotating parts with the heatexchangers.

While the present invention has been illustrated by the description ofexemplary processes and system components, and while the variousprocesses and components have been described in considerable detail,applicant does not intend to restrict or in any way limit the scope ofthe appended claims to such detail. Additional advantages andmodifications will also readily appear to those ordinarily skilled inthe art. The invention in its broadest aspects is therefore not limitedto the specific details, implementations, or illustrative examples shownand described. Accordingly, departures may be made from such detailswithout departing from the spirit or scope of applicant's generalinventive concept.

1. A subsurface power generating system comprising: a frame; a firstelectric generator supported by the frame, the first electric generatoroperably connected to a first vertical rotor; a second electricgenerator supported by the frame, the second electric generator operablyconnected to a second vertical rotor; a first louver operably connectedto the first vertical rotor and including a front side, and a back side,and pivotable between a first position whereat the backside is incontact with a first pivot limiting structure, and a second positionwhereat the backside is not in contact with the first pivot limitingstructure; and a second louver operably connected to the second verticalrotor and including a front side, and a back side, and pivotable betweena third position whereat the backside is in contact with a second pivotlimiting structure, and a fourth position whereat the backside is not incontact with the second pivot limiting structure.
 2. The system of claim1, wherein: the first louver pivots about a first pivot axis; the firstpivot axis extends through the first louver at a location closer to aleading edge of the first louver than to a trailing edge of the firstlouver, such that water impinging on the front side of the first louvergenerates a force biasing the first louver toward the first position;the second louver pivots about a second pivot axis; and the second pivotaxis extends through the second louver at a location closer to a leadingedge of the second louver than to a trailing edge of the second louver,such that water impinging on the front side of the second louvergenerates a force biasing the second louver toward the third position.3. The system of claim 2, wherein: the first pivot axis intersects thefirst vertical rotor; and the second pivot axis intersects the secondvertical rotor.
 4. The system of claim 2, wherein: the first pivotlimiting structure is a leading edge portion of a third louver; and thesecond pivot limiting structure is a leading edge portion of a fourthlouver.
 5. The system of claim 4, wherein: the first louver and thethird louver are mounted on a first louver panel; the second louver andthe fourth louver are mounted on a second louver panel; a third louverpanel and a fourth louver panel are operably connected to the firstvertical rotor and are spaced equidistantly apart from the first louverpanel; and a fifth louver panel and a sixth louver panel are operablyconnected to the second vertical rotor and are spaced equidistantlyapart from the second louver panel.
 6. The system of claim 5, whereinthe first louver, the second louver, the third louver, and the fourthlouver are neutrally buoyant at an operating depth.
 7. The system ofclaim 1, wherein the frame defines a first channel, and a secondchannel, the system further comprising: a first guide wire extendingthrough the first channel; and a second guide wire extending through thesecond channel.
 8. The system of claim 7, wherein the frame ispositively buoyant.
 9. The system of claim 7, wherein the frame iscontrollably buoyant between a positively buoyant state, a neutrallybuoyant state and a negatively buoyant state.
 10. The station of claim9, further comprising an anchor operatively coupled to the first guidewire, and the second guide wire.
 11. The station of claim 7, furthercomprising: a first subsurface buoy operatively coupled to the firstguide wire; and a second subsurface buoy operatively coupled to thesecond guide wire.
 12. The station of claim 11, further comprising: afirst traction device operatively coupled to the first guide wire andthe frame for controlling relative movement between the first guide wireand the frame; and a second traction device operatively coupled to thesecond guide wire and the frame for controlling relative movementbetween the second guide wire and the frame.
 13. A method of generatingelectrical power from a water current comprising: positioning a firstlouver within a water current; impinging a front side of the firstlouver with the water current; pivoting the first louver into contactwith a first pivot limiting structure using a first force generated bythe impinging water current; transferring a second force from the watercurrent to the first pivot limiting structure; and rotating a firstvertical rotor operably connected to a first electrical generator withthe transferred second force.
 14. The method of claim 13, furthercomprising: positioning a second louver within the water current;impinging a front side of the second louver with the water current;pivoting the second louver into contact with a second pivot limitingstructure using a third force generated by the impinging water current;transferring a fourth force from the water current to the second pivotlimiting structure; and rotating a second vertical rotor with thetransferred fourth force.
 15. The method of claim 14, wherein: pivotingthe first louver comprises pivoting the first louver about a first axisof rotation which is parallel with a velocity vector of the watercurrent; and pivoting the second louver comprises pivoting the secondlouver about a second axis of rotation which is parallel with thevelocity vector of the water current.
 16. The method of claim 14,wherein: pivoting the first louver comprises pivoting the first louverinto contact with a third louver; and pivoting the second louvercomprises pivoting the second louver into contact with a fourth louver.17. A subsurface power generating system comprising: a frame; a firstelectric generator supported by the frame, the first electric generatoroperably connected to a first vertical rotor; a first louver operablyconnected to the first vertical rotor and including a front portion, anda back portion, and pivotable between a first position whereat the backportion is in contact with a first pivot limiting structure, and asecond position whereat the back portion is not in contact with thefirst pivot limiting structure; and a first bar extending through thefirst louver and defining an axis of rotation for the first louver suchthat the first louver is cantilevered toward the second position fromthe first position in response to a current contacting the back portionof the first louver and cantilevered toward the first position from thesecond position in response to the current contacting the front portionof the louver.
 18. The system of claim 17, further comprising: a secondelectric generator supported by the frame, the second electric generatoroperably connected to a second vertical rotor; a second louver operablyconnected to the second vertical rotor and including a front portion,and a back portion, and pivotable between a third position whereat theback portion is in contact with a second pivot limiting structure, and afourth position whereat the back portion is not in contact with thesecond pivot limiting structure; and a first bar extending through thesecond louver and defining an axis of rotation for the second louversuch that the second louver is cantilevered toward the fourth positionfrom the third position in response to a current contacting the backportion of the second louver and cantilevered toward the third positionfrom the fourth position in response to the current contacting the frontportion of the louver.
 19. The system of claim 18, wherein: the firstelectric generator is operably connected to the first vertical rotorthrough a first clutch; and the second generator is operably connectedto the second vertical rotor through a second clutch.